We've used Monster Cart Upsell for several years now and it works well. Their customer support is also very quick to respond. Their live chat isn't always available, but if you start a chat they will email you back pretty quick. I've also given them access to my online store several times and they're able to fix issues for me. 5/5 stars!

Great customer service and customizations on various cart types. I've been really happy with the adaptability of the carts/offers and have been able to easily tie the aesthetic in to match my store and product. Encountered some issues integrating with other high-level apps in store, but with the devs help we have been able to navigate through that as well. Thanks Monster Cart team :)

Solid app, great customer support. I found and reported a bug which the team promptly fixed within 48 hours.

We requested a refund because the app continued to run even though we believed it had been uninstalled. We haven’t received any response to our email. We generated 0 euros via this app.

That’s a wonderful app. I’ve seen other apps that are not as fast and are very heavy to run. This one is amazing, especially because of the kind of support they provide.

At BauUniverso™, we move fast — and so do they! I had a technical issue on my store that needed urgent attention. The MonsterApps team jumped in immediately, diagnosed the problem, and fixed it in just a few hours. Not only did they solve the main issue, but they also double-checked that all colors, sizes, and features were perfectly updated and running smoothly. Their communication was crystal clear, fast, and human — something you don’t often find in tech support. In an industry where delays are common, MonsterApps stands out for their speed, skill, and genuine care for their clients. They didn’t just meet expectations — they went beyond. Highly recommend them to anyone who values reliable, proactive, and high-quality support. Thanks again, MonsterApps — I’ll be recommending you every chance I get! — Founder & CEO — BauUniverso™

Charlene was very helpful and easy to chat with. Made my experience with Monster Cart seamless, highly recommend.

I can’t recommend the Monster Checkout Cart app enough! It’s incredibly customizable, easy to use, and integrates seamlessly with my Shopify store. What really sets it apart is the customer service — they respond so quickly and go above and beyond to help with any questions or tweaks I need. I love how flexible the app is, and it has made a huge difference for my store’s checkout experience. Truly impressed and very happy with both the app and the support team!

The Monstercart upsell app looks amazing. I'm currently still going through setup, and have had an incredible experience with support helping me through some of my initial setup already.

Excellent experience with customer service team (Angelica in particular). Responses are always prompt and they've been very helpful in getting the cart to show on our site!